r IProblem I Type Where Abend Occurs Distinguishing Characteristics
1------------------------------------------------------------------ Wait (cont.) , Enabled CP IThe processor console light is on, but the
wait I system accepts interrupts from I/O devices.
Disabled
virtual
machine wait
Enabled
virtual
machine wait
Disabled RSCS wait IThe VM/370 Control program does not allow a
virtual machine to enter a disabled wait
state or certain program loops. Instead, CP issues one of the following messages: DMKDSP450W CP ENTERED; DISABLED WAIT PSW DMKDSP451W CP ENTERED; INVALID PSW DMKDSP452W CP ENTERED; EXTERNAL INTERRUPT LOOP DMKDSP453W CP ENTERED; PROGRAM INTERRUPT LOOP A PSW enabled for I/O interrupts is loaded.
Nothing happens if an I/O device fails to
issue an I/O If a program is
taking longer to execute than expected,
periodically issue the CP QUERY TIME. If the processing time remains un­
changed, there is probably a virtual
machine enabled wait. CMS types a blip character fer every 2
seconds of elapsed processing time. If the
program does not end and blip characters
stop typing, an enabled wait state probably The RSCS operator is notified of the wait
state by CP issuing the message DMKDSP450W CP ENTERED; DISABLED WAIT PSW If, in addition, the .essage DMTINI402T IPL DEVICE READ I/O ERROR appears on the RSCS console, an unrecover­
able error has occurred while reading the RSCS nucleus fro. DASD storage. RSCS enters a disabled wait state with a code
of 011 in the PSW. If a program check occurs before the
program check handler is activated, RSCS enters a disabled wait state with a code of 007 in the PSW. Figure 2. VM/370 Problem Types (Part 5 of 6) 12 IBM 9h/37G System programmer·s Guide
,

r
Problem
Type Where Abend Occurs Distinguishing Characteristics Wait IDisabled RSCS IIf a program check occurs after the program (cont.) I wait (cont.) I check handler is activated, RSCS enters a
Loop I disabled wait state with a code of 001 in the PSi. One of the following messages may also appear on the RSCS console: DMTREX090T PROGRAM CHECK IN SUPERVISOR RSCS SHUTDOWN DMTREX091T INITIALIZATION FAILURE -- RSCS SHUTDOWN Enabled RSCS IRSCS has no task ready for execution. A
wait I PSW, for external and I/O CP disabled
loop I interrupts, is loaded with a wait code of
i all zeros. IThe processor console wait light is The I problem state bit of the real PSi is off. I No I/O interrupts are accepted. IThe program is taking longer to execute than I anticipated. Signaling attention from the Virtual machine
disabled loopl terminal does not cause an interrupt in the I virtual The virtual machine opera­ I tor cannot communicate with the virtual Virtual machine
enabled loop I machine's operating system by signalling I attention. IExcessive processing time is often an indi­ I cation of a loop_ Use the CP QUERY TIME I command to check the elapsed processing I time. In CMS, the continued typing of the I blip characters indicates that processing I time is elapsing. If time has elapsed, I periodically display the virtual PSi and I check the instruction address. If the same
1 instruction, or series of instructions, I continues to appear in the PSi, a loop I probably Figure VM/370 Problem Types (Part 6 of 6)
ANALYZING THE PROBLEM Once the type of problem is identified, its cause must be determined.
There are recommended procedures to follow. These procedures are
helpful, but do not identify the cause of the Froblem in every case. fe resourceful. Use whatever data you have available. If the cause of the
problem is not found after the recommended debugging procedures are
followed, it may be necessary to undertake the tedious job of
desk-checking.
The section "How To Use VM/370 Facilities To Debug" describes
procedures to follow in determining the cause of various problems that
can occur in the Control Program or in the virtual machine. See the VM/370 £MS for information on using VM/370 facilities to
debug a problem program.
Part 1. Debugging with VM/370 13